An image reading device for reading image information is, for example, disclosed in FIG. 1 of Japanese Patent Application Publication Laid-Open No. 2007-249475 (referred to as Patent Document 1), by which an image included in a hologram region of a target to be light-irradiated is read out using a white light source, etc., and the target is determined to be true or false.
Another image reading device is disclosed in FIG. 1 and paragraph [0035] of Japanese Patent Application Publication Laid-Open No. H11-215301 (referred to as Patent Document 2), which is configured in such a manner that two slants 16a and 16b whose slant angles are different from each other are provided midway along a light-irradiation channel 14 sandwiched between two internal walls 15a and 15b, the slants are positioned above LED chips 6, and the light-irradiation channel is made to approach an image reading region S as approaching the top.
However, in the device disclosed in Patent Document 1, first light sources 4 that irradiate a portion 3a, to be irradiated with light, of a hologram region, and second light sources 6 that irradiate a portion 3b, to be irradiated with light, of the hologram region after having been conveyed by a predetermined amount thereof are provided; therefore, a problem has occurred that not only illumination units are needed to be arranged at positions different from each other in its conveying direction, but also, because reading of the same pixels is performed after a certain time has elapsed, a target to be irradiated with light has to be accurately conveyed.
In the device disclosed in Patent Document 2, by providing LED chips 6 in the lower portion of a light emitting channel 14, and by reflecting light, emitted from the LED chips 6, at slants 16a and 16b arranged above the chips, an image reading region S positioned at the top of the device is illuminated; therefore, a problem has occurred that, because its light-traveling path is long in a heightwise direction, the device size is comparatively large.